So recently I left my laptop unplugged for a few minutes, and since it has nearly zero battery, it cuts off without any graceful shutdown.
After turning it on, it says (via BIOS) that the clock was reset or something, so I went into the BIOS and set it to the correct time, and merrily booted up.
Filesystem check happened, etc, nothing else seemed to be off. The problem is that updating apt results in all my ppas having invalid signatures, and apt always warning me about unsigned packages when I install them.
I assume this is related to the clock resetting - nothing else seems to be out of place. Is there anyway to reset apt so that it will stop complaining about the signatures?